Abstract: The Xinfatun rock body, located in Horqin Youyi Zhongqi, Inner Mongolia, is dominated by granodiorite, with SHIRMP U-Pb dating age of 138±10 Ma, which belongs to Early Cretaceous. Geochemical data show that the rock body is of cale-alkaline series, with enrichment in K, Rb, Ba and Th and relative deficiency of Sr, Ta, Nb, P and Ti. The REE distribution curves are rightward inclined, showing obvious fraction of LREE and HREE and negative anomaly of Eu. These characteristics indicate that the Xinfatun rock body was formed in late orogenic environment and was the product of crustal uplift after plate collision.